strcspn, wcscspn, _mbscspn, _mbscspn_l

Article
07/22/2011

Returns the index of the first occurrence of a character in a string that belongs to a set of characters.

size_t strcspn(
   const char *str,
   const char *strCharSet 
);
size_t wcscspn(
   const wchar_t *str,
   const wchar_t *strCharSet 
);
size_t _mbscspn(
   const unsigned char *str,
   const unsigned char *strCharSet 
);
size_t _mbscspn(
   const unsigned char *str,
   const unsigned char *strCharSet,
   _locale_t locale
);

Parameters

str
Null-terminated searched string.
strCharSet
Null-terminated character set.
locale
Locale to use.

Return Value

These functions return the index of the first character in str that is in strCharSet. If none of the characters in str is in strCharSet, then the return value is the length of str.

No return value is reserved to indicate an error.

Remarks

wcscspn and _mbscspn are wide-character and multibyte-character versions of strcspn. The arguments of wcscspn are wide-character strings; those of _mbscspn are multibyte-character strings.

_mbscspn validates its parameters. If either str or strCharSet is a null pointer, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, the function returns 0 and sets errno to EINVAL. strcspn and wcscspn do not validate their parameters. These three functions behave identically otherwise.

The output value is affected by the setting of the LC_CTYPE category setting of the locale; see setlocale for more information. The versions of these functions without the _l suffix use the current locale for this locale-dependent behavior; the versions with the _l suffix are identical except that they use the locale parameter passed in instead. For more information, see Locale.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
_tcscspn	strcspn	_mbscspn	wcscspn
n/a	n/a	_mbscspn_l	n/a

Requirements

Routine	Required header
strcspn	<string.h>
wcscspn	<string.h> or <wchar.h>
_mbscspn, _mbscspn_l	<mbstring.h>

For additional compatibility information, see Compatibility in the Introduction.

Example

// crt_strcspn.c

#include <string.h>
#include <stdio.h>

void test( const char * str, const char * strCharSet )
{
   int pos = strcspn( str, strCharSet );
   printf( "strcspn( \"%s\", \"%s\" ) = %d\n", str, strCharSet, pos );    
}

int main( void )
{
   test( "xyzbxz", "abc" );
   test( "xyzbxz", "xyz" );
   test( "xyzbxz", "no match" );
   test( "xyzbxz", "" );
   test( "", "abc" );
   test( "", "" );
}

strcspn( "xyzbxz", "abc" ) = 3
strcspn( "xyzbxz", "xyz" ) = 0
strcspn( "xyzbxz", "no match" ) = 6
strcspn( "xyzbxz", "" ) = 6
strcspn( "", "abc" ) = 0
strcspn( "", "" ) = 0

.NET Framework Equivalent

System::String::Substring